Quick question spurred on by another thread - when selecting a powder for a load, and it is not in the published load data tables, how far up or down the chart is the normal range for any particular powder? For example, instead of using Varget (#108) in 6.5 Creedmoor, and using IMR 4166 (#100), is that generally acceptable? I realize that the IMR 4166 is faster, but is it in the correct range? I only mention those 2 powders because on IMR’s website, it touts 4166 performance comparable to Varget, even though charge weight is not grain for grain load size wise. Any help is appreciated!
Powder Burn Chart Question
- Thread starter Wyo82
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LightninST
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Hodgdon has (10) different loads for 6.5 using 4166
IMHO, there's a bit more to it than just burn rate though. (I've found load data for 6.5 CM using 8208 XBR all the way to Hybrid 100 (90 to 128 on the chart)
Pretty sure some will work better than others.
Sorry, no experience with 4166 here.
IMHO, there's a bit more to it than just burn rate though. (I've found load data for 6.5 CM using 8208 XBR all the way to Hybrid 100 (90 to 128 on the chart)
Pretty sure some will work better than others.
Sorry, no experience with 4166 here.
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Let me reframe my question. Say I want to use Varget in my 6.5 Creedmoor - but Varget is unavailable, how far up or down the list from Varget can I expect to be able to choose from as far as rifle powders go? Is it within 10 spots either direction, 5 spots, or 20?
Just throwing this out there, not claiming to speak as an expert or experienced on the matter. Burn rates are only a small part of the picture, powders trend to also burn differently at different pressures. Developing loads based on burn rate alone seems to me to be a very high risk activity. I'm sure it can be done safely, but I would think a high level of experience, knowledge and likely some non standard equipment would be involved.
Right, Im just curious because I’ve seen a lot of posts state “ well as long as you don’t go any faster than X powder and slower than Z powder you’ll be ok”....so I was just curious as to if there was a general range that’s used. I realize the chart may have a powder listed that has a burn rate 1 spot away from your powder you are looking at and it may be not applicable to rifle loads or whatever you are shooting. I also realize burn rate is just a small part of the entire formula when it comes to reloading. Maybe I’m thinking too much into it and asking a dumb question.
I think I get what you're saying, not dumb at all. I'm under the impression the chart just gives a rough idea of powders that may give relatively similar results. I don't think it is meant to be used in the absence of published data, just to compliment it.
The closer they are on the chart, the more likely they are to give similar results in a given application.
The closer they are on the chart, the more likely they are to give similar results in a given application.
LightninST
Member
Better to ask than try and fail when reloading !
Hodgdon has a online loading site , plug in your caliber,bullet weight and leave powder choice blank it will show all their loads for their powders .
http://www.hodgdonreloading.com/
Hodgdon has a online loading site , plug in your caliber,bullet weight and leave powder choice blank it will show all their loads for their powders .
http://www.hodgdonreloading.com/
denton
Member
The powder burn rate chart is in rank order. The difference between two adjacent powders in the chart might be entirely different from two other adjacent powders. All you can say is that powders higher in the chart are faster than powders lower in the chart. You can't say there is any particular difference between two powders.
Since it is only ordinal data, not interval data, there is no answer to the OP's question.
Since it is only ordinal data, not interval data, there is no answer to the OP's question.
fxvr5
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The simple answer is that you can use any powder for which there is load data - no matter where it is on a burn rate chart.
Also, different burn rate charts place powders in different places. Hodgdon's serial/linear rank chart is constrained by it being serial/linear.
Also, different burn rate charts place powders in different places. Hodgdon's serial/linear rank chart is constrained by it being serial/linear.
It is a Relative burn rate chart. All you can tell for sure from it is if a powder is ranked faster or slower than another. It in no way indicates how much faster or slower. Number 10 might be 1% slower than number 9, while number 11 is 5% slower than #9 and number 12 is only 5.5% slower than #9.
(Completely made up numbers to make the point)
(Completely made up numbers to make the point)
DocRock
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If from a curiosity standpoint, look up published data for a given bullet weight and then look at all the powders for which data is supplied and locate them on the burn rate chart. Depending on the cartridge in question, it can be quite a wide range (of relative burn rates).
NMexJim
Member
The general rule as I know it when the bullet remains the same and when substituting powders becomes necessary is to try and match velocity and powder density (case fill).
Lee Precision, Inc. - VMD explanation Here's an intro to the subject of calculating powder volume.
I haven't made a study of it, but I associate slower burn with more volume. I'm sure there are exceptions.
Widener's has a good intro Guide to Smokeless Powder (wideners.com) which will get you going, I hope.
Just in case the word "efficiency" has popped into your mind somewhere in here, I won't wander off into the efficiency of gunpowder and will leave you to search this forum and elsewhere for that topic. You'll find it up at the top of the burn chart. Conflagration anyone?
Lee Precision, Inc. - VMD explanation Here's an intro to the subject of calculating powder volume.
I haven't made a study of it, but I associate slower burn with more volume. I'm sure there are exceptions.
Widener's has a good intro Guide to Smokeless Powder (wideners.com) which will get you going, I hope.
Just in case the word "efficiency" has popped into your mind somewhere in here, I won't wander off into the efficiency of gunpowder and will leave you to search this forum and elsewhere for that topic. You'll find it up at the top of the burn chart. Conflagration anyone?
Thank you for the info - that’s more in the area of what I was looking for.
Here is where you find your load info for IMR 4166 used in the 6.5 CM.
https://shop.hodgdon.com/reloading-...21.2056992500.1613197263-938485596.1612404932
Punch in your cartridge of 6.5 Creedmoor then put in the MANUFACTURER, then punch IMR 4166 & push UPDATE DATA
https://shop.hodgdon.com/reloading-...21.2056992500.1613197263-938485596.1612404932
Punch in your cartridge of 6.5 Creedmoor then put in the MANUFACTURER, then punch IMR 4166 & push UPDATE DATA
Look at a loading manual. Note range of powders shown. Look at burn rate chart. Notice that the powders cover a rather wide burn rate range.
Next, look at three or more burn rate charts and note how varget, or any other powder, will move around from position chart to chart.
What a burn rate chart should list is test method and test results.
Next, burn rate varies based on pressure and temperature, so it varies from cartridge to cartridge and with bullet weight.
Burn rate chart means almost nothing. Available data means everything.
Next, look at three or more burn rate charts and note how varget, or any other powder, will move around from position chart to chart.
What a burn rate chart should list is test method and test results.
Next, burn rate varies based on pressure and temperature, so it varies from cartridge to cartridge and with bullet weight.
Burn rate chart means almost nothing. Available data means everything.
Burn rate is only ONE factor in a powder's ballistic response:
- Burn Rate/sec (at the start of ignition -- i.e., "The Chart" -- after which everything changes)
- Energy content (Heat/Kg)
- Ratio of specific heats (specific heat at constant pressure vs and the specific heat at constant volume)
- Progressive (or de-gressive) burning rate with increasing pressure)
- Progressive burning limit (at which point increasing burn rate quits/tops out)
- ...and last but not least: a "Factor b" to balance the thermodynamics
As you can see, don't EVER use simple Burn Rate to estimate loading results.
- Burn Rate/sec (at the start of ignition -- i.e., "The Chart" -- after which everything changes)
- Energy content (Heat/Kg)
- Ratio of specific heats (specific heat at constant pressure vs and the specific heat at constant volume)
- Progressive (or de-gressive) burning rate with increasing pressure)
- Progressive burning limit (at which point increasing burn rate quits/tops out)
- ...and last but not least: a "Factor b" to balance the thermodynamics
As you can see, don't EVER use simple Burn Rate to estimate loading results.
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Blue68f100
Member
Then you can add the lot to lot difference. I've seen it year after year that the order changes depending on lot.
Your other option is to wildcat a round. This is were Quick Load will help keep you out of trouble provided you put in all the needed info, case volume.
What I have found with the 4166 is that it produces approx 100 fps less than H4350 with the same bullet, loads worked up separately. I have found it normally gives me a slightly lower SD. I have found I prefer it if I'm shooting lighter bullets 130gr and less.
Your other option is to wildcat a round. This is were Quick Load will help keep you out of trouble provided you put in all the needed info, case volume.
What I have found with the 4166 is that it produces approx 100 fps less than H4350 with the same bullet, loads worked up separately. I have found it normally gives me a slightly lower SD. I have found I prefer it if I'm shooting lighter bullets 130gr and less.
bdb242
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This thread is an example of the issues I ran into developing loads for custom caliber/case size changes for my rifles. I searched around and finally bought a Load From a Disc program that answered a lot of questions with the variables available in the program. Unfortunately the disc was damaged and ruined. The replacement I found is the Quick Load program I found in the UK. It is not as versatile as the Load From a Disc but it is updated yearly for new components. It is not inexpensive but has proved to be very accurate so far and much safer than trial and error.
Charlie98
Member
That's why I hate that chart posted in #2 above. It doesn't really relate the powders to each other, it just lists them numerically... with no reference.
Try this chart...
http://www.accuratepowder.com/wp-content/uploads/2010/12/burn_rates.pdf
...it lists powders in relation to each other based on burn rate. It isn't the end all, as MEHavey mentions, there are other factors, but it's a better chart than the one posted above.
Try this chart...
http://www.accuratepowder.com/wp-content/uploads/2010/12/burn_rates.pdf
...it lists powders in relation to each other based on burn rate. It isn't the end all, as MEHavey mentions, there are other factors, but it's a better chart than the one posted above.
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